Water content indicator for liquid mixtures



June 1, 1937. J. L. ODONNELL WATER CONTENT INDICATOR FOR LIQUID MIXTURES Filed Aug. 20, 1934 j/wi/yron. Jmas 440m 020mm.

Patented June 1, 1937 UNITED STATES WATER CONTENT INDICATOR FOR LIQUID MIXTURES James Lloyd O'Donnell, Long Beach, Calif.

Application August 20, 1934, Serial No. 740,666

8 Claims.

useful features which successfully overcome dimculties present in apparatuses heretofore in The fact that water-bearing oil as an electrolyte, has a high negative temperature coefilcient of resistance, the resistance decreasing rapidly 30 with increased temperature.

The fact that with ordinary means, involving the introduction of sufficiently high voltage between the terminals of electrodes immersed in oil to give a suitable deflection, the structure of the oil would invariably be broken down, resulting in very erratic readings on the meter, which bear no accurate relation to the comparative water content of the oil.

The fact that resistance of water-bearing oil varies with different specific gravities of oil, which is true, not only as between two samples of-nominally different specific gravity, but also between two samples of the same nominal specific gravitybut difierent water contentowing to the reduc- 5 tion in specific gravity with reduction of water content.

An object of my invention is to overcome the above named-difliculties by passing a very small current thru the liquid sample so that said cur- 50 rent will have no tendency to break up the structure of the sample.

Also, my instrument is automatically compensated for difference in temperatures or specific gravity with every reading. 66 In the drawing Figure lis a longitudinal sectional view of the electrode assembly and a wiring diagram of the apparatus to indicate the percentage of water present.

Figure 2 is a wiring diagram of a modified type, utilizing only one tube.

Referring more particularly to the drawing, my device consists of two vacuum tubes I and 2, a

power transformer 3, ,an electrode assembly I, a milliammeter 5, a variable resistor 6, a double pole, double throw switch I, lamps .8 and 9, a resistance III, a choke coil II, and a condenser I2. The choke coil is inserted in the circuit for the purpose of preventing certain low frequencies from passing thru the circuit.

Current is supplied to the primary winding of the transformer 3 thru the leads I3. The current supplied is preferably A. C. The filaments of the tubes I and 2 are heated by current from the windings I 4, I5, respectively, of the transformer 3. Plate current for the tube I flows from the winding I6 of the transformer 3. A resistance I! is interposed in the lead I8, which extends from the winding I6 to the plate of the tube I. This resistance has a value of approximately 15,000 ohms, more or less. The lead I8 also extends to the windings of the choke coil I I. The core of this choke coil is grounded, as shown at I9. The core of the transformer 3 is also grounded, as shown at 20.

The condenser I2 is interposed in a lead, 2|,

" which lead is tapped onto the wire 22, which last named wire extends from the grid of the tube I to one binding post of the milliammeter 5. The condenser I2 has a capacity of approximately .1 micro-farad.

A wire 23 extends from the second terminal or binding post of the milliammeter to one end of the coil I6. The variable resistor Ii is shunted across the terminals of the milliammeter.

The electrode assembly 4, which is immersed in the sample of liquid to be tested, consists of a metal tube 24 which tube depends froma head 25 formed of a suitable insulating material. A metal rod 26 also depends from the head 25 and is positioned within the tube 24 and equally spaced from the inner surface of said tube.

A wire 21 extends from the tube 24 to the grid of the tube 2. A wire 28 extends from the rod 26 to a central post of the double throw switch 1. The double throw switch I allows the electrodes 24 and 25 tobe connected either between the grid and ground of the tube 2, or between the grid and plate of the tube 2.

The resistance I0 is electrically connected at one end to a binding post 29 of the switch I. The other end of this resistance is connected to ground. The value of this resistance is approximately megohms, more or less. 4 5 The binding post 30 of the switch I is electrically connected to the plate of the tube 2. Thus, it will be evident that when the switch 'I is thrown so as to engage the post 29, the electrodes will be connected between the grid of the tube 2 and ground. When the switch is thrown so as to engage the post 30, the electrodes will be connected between the grid and the plate of tube 2.

When the switch I is thrown so as to engage the post 29, it is in the index position. With the switch in "index position, and with current supplied to the tubesl and 2, the operation of the device is as follows: plate current flows from one end of the winding 16 thru resistance I! to the plate of the tubel, thence inside the tube I from 20 plate to filament, thence to the winding l4, then out thru the center tap of the winding thru lead 3| to the plate of the tube 2, then to the filament of tube 2, thence thru leads to the winding 15 out thru a center tap on the winding 15 thru a wire 32 to the milliammeter 5, and then thru the wire 23 to the other end of the coil i6.

If the parts 24 and' 26 are not immersed in a liquid sample, the flow of plate current will be so small as to give a barely perceptible reading 30 or no reading at all on the milliammeter 5. This is due to the fact that the plate resistance of tube 2 is so high asto place a veryhigh negative bias on the grid of the tube i.

If the parts 24 and 26 are now immersed in a liquid, the conductivity of the liquid will allow electrons to leak oif of the grid in the tube 2 to ground. This immediately lowers the plate resistance of the tube 2 and allows an increased flow of plate current. In practice, my device is so arranged that the deflection obtained on the milliammeter 5 with the switch I in the index" position, is small. By means of the variable resistor 6, the reading obtained in every sample of oil tested, is adjusted at the time of the test to a mark on the face of the dial of the milliammeter, which may be marked Index.

With the switch! in the index position, the actual value of plate current passing will vary with different temperatures of oil, and with different specific gravities, but will not be appreciably affected by different percentages of water in the oil or liquid sample.

Thus, it will be evident that with the method of setting each test reading to a definite zero position on the milliammeter, I have an absolutely reliable compensation for difference in temperature or specific gravity, as well as for changes in.line voltage or other electrical characteristics. 60 If the switch I is thrown over so as to engage the post 30, this will be known as the read position. The members 24 and 26 are now connected between the plate and grid of the tube 2. This results in a larger deflection of the 65 needle of the milliammeter 6. The amount of deflection of this needle is accurately proportional to the percentage of water in the sample in which the members 24 and 26 are immersed. The dial of the milliammeter 6 is calibrated so 70 as to read directly in percentage of water present in the sample. serve to indicate to the operator in which position the switch I is resting, and also indicate whether the current is on. 75 In Figure 2, the leads ll, 94 extend from the .tures, comprising a power transformer,

The signal lamps 6 and 9 rod and tube, respectively, of the electrode assembly 4. The lead 33 extends to the grid of the tube 35. The lead 34 extends to one end of the winding 36 of the transformer 31. This transformer is the usual audiofrequency type 5 used in radio circuits. A battery 38 is interposed in the line, extending from one terminal of the milliammeter 39 to the plate of the tube 35. One end of the winding 40 of the transformer 31 is also tapped into the lead from the battery 36 10 to the tube 35. The other end of the winding 36 is connected to a binding post of the milliammeter '39. The other end of the winding 40 is connected thru the condenser 4| to a middle tap of the secondary winding 42 of the power 15 transformer 43. Filament current for the tube 35 is supplied from the winding 42. With this arrangement, only one tube is utilized and the dial of the milliammeter is calibrated to read directly in percentage of water present in the 20 sample in which the members 24 and 26 are immersed.

Having described my invention, I claim:

1. The method of indicating the water content in liquid mixtures, consisting of first meas- 25 uring the flow of current between electrodes immersed in the liquid with a small voltage imposed upon the electrodes, and then again measuring the current passing between the electrodes with a higher voltage imposed upon said electrodes, the first voltage being insufil'cient to cause disassociation of the water and the second voltage being sufficient to cause disassociation of the water.

.2. A water content indicator for water mixtures, comprising a pair of electrodes immersed in the liquid, a milliammeter, a multi-element tube, said electrodes, milliammeter and tube being con nected in an electrical circuit, power input means in said circuit, said milliammeter being con- 40 nected between one element of the tube and said power input means, said electrodes being connected between the power input means and another eiement of the tube, and manual means in said circuit electrically connected to the elec- 45 trodes, whereby said electrodes may be manually connected to the power input means and one element of the tube, or between said element of the tube and ground.

3. A water content indicator for liquid mix- 50 two multi-element tubea'a milliammeter, electrically connected between an element of one of the tubes and the transformer, a pair of electrodes immersed in the liquid, said electrodes being electrically connected between an element of the second tube and the transformer, and an electrical circuit including said tubes and the transformer.

4. A water content indicator for liquid mixtures, comprising a power transformer, two multielement tubes, a milliammeter, electrically connected between an element of one of the tubes and the transformer, a pair of electrodes immersed in the liquid, said electrodes being electrically connected between an element of the second tube and the transformer, an electrical circuit including said tubes and the transformer, and a choke coil in the electrical circuit.

5. A water content indicator for liquid mixtures, comprisinga power transformer, two multielement tubes, 9. milliammeter, electrically connected between an element of one of the tubes and the transformer. a pair of electrodes immersed in the liquid, said electrodes being elec- 76 trically connected between an element of the sec-- ond tube and the transformer, an electrical circuit including said tubes and the transformer, a double pole switch, one side of said switch being grounded and the other side of said switch being connected to an element of the second tube, one of said electrodes being electrically connected to said switch whereby the circuit, including the electrodes, may be manually changed to include two elements of said second tube or one element of said second tube and ground.

6. A water content indicator for liquid mixtures, comprising a power transformer, two multielement tubes, a milliammeter, electrically connected between an element of one of the tubes and the transformer, a pair of electrodes immersed in the liquid, said electrodes being electrically connected between an element of the second tube and the transformer, an electrical circuit including said tubes and the transformer, a choke coil in the electrical circuit, a double pole switch, one side of said switch being grounded and the other side of said switch being connected to an element of the second tube, one of said electrodes being electrically connected to said switch whereby the'circuit, including the electrodes, may

be manually changed to include two elements of said second tube or one element of said second tube and ground.

'7. A water content indicator for liquid mixtures, comprising a power transformer, a pair of multi-element tubes, a milliammeter, said milliammeter being connected between the power transformer and an element of one of the tubes,

a pair of electrodes immersed in the liquid, said electrodes being connected between-two elements of the second tube, and an electrical circuit including the tubes and the transformer.

8. A water content indicator for liquid mixtures, comprising a power transformer, a pair of multi-element tubes, a milliammeter, said milliammeter being connected between the power transformer and an element of one of the tubes, 2. pair of electrodes immersed in the liquid, said electrodes being connected between two elements of the second tube, an electrical circuit including the tubes and the transformer, and a change over switch whereby said electrodes are connected between two elements of the second tube, or between one element of the second tube and ground.

JAMES LLOYD ODONNELL. 

